Visual detection of aldehyde gases using a silver-loaded paper-based colorimetric sensor array.

The small molecule aldehydes are volatile organic compounds (VOCs), possessing cytotoxicity and carcinogenicity. Long-term exposure can pose a serious threat to human health. Based on an in-situ reduction colorimetric method to generate silver nanoparticles and induce colorimetric response, we proposed a silver-loaded paper-based colorimetric sensor array for visually detecting and differentiating five relatively common trace small molecule aldehyde gases. The silver ions are immobilized onto a porous filter paper and stabilized by complexing agents of branched polyethyleneimine, ethylenediamine, and 1,6-diaminohexane, respectively. The as-fabricated sensor array expresses remarkable stability and capacity to resist humidity. The qualitative analysis reveals that the sensor array has excellent selectivity for aldehyde gases and displays remarkable anti-interference ability. The quantitative analysis indicates that the sensor array exhibits superior sensitivity for five aldehyde gases, with limits of detection (LODs) of 9.0 ppb for formaldehyde (FA), 3.1 ppm for acetaldehyde (AA), 3.5 ppm for propionaldehyde (PA), 23.8 ppb for glutaric dialdehyde (GD), and 71.5 ppb for hydroxy formaldehyde (HF), respectively. Importantly, these LODs are all comfortably below their respective permissible exposure limits. A unique colorimetric response fingerprint is observed for each analyte. Standard chemometric methods illustrate that the sensor array has excellent clustering capability for these aldehyde gases. Additionally, the sensor array's response is irreversible and possesses outstanding performance for cumulative monitoring. This colorimetric sensor array based on silver ions reduced to silver nanoparticles offers a novel detection method for the continuous, ultrasensitive, and visual detection of trace airborne pollutants.

The Synthesis of Functionalized Carbonized Polymer Dots via Reversible Assembly of Oligomers for Anti-Counterfeiting, Catalysis, and Gas storage.

Carbonized polymer dots (CPDs) have shown exceptional potential across a wide range of applications. However, their practical utilization is significantly greatly impeded by the lack of precise control over their structures and functionalities. Consequently, the development of controlled synthesis strategies for CPDs with well-defined structures and tailored functionalities remains a critical challenge in the field. Here, the controlled synthesis of functional CPDs with reversible assembly properties via airflow-assisted melt polymerization, followed by a one-step post-synthetic doping strategy, is reported. This synthetic approach achieves high product yield, uniform and tunable structures, as well as customized functionalities including solid-state emission, enhanced catalytic performance (3.5-45 times higher than conventional methods), and selective gas storage in the resulting CPDs. The ability to tailor the properties of CPDs through controlled synthesis opens up new opportunities for their practical application in photocatalysis and gas storage.

Cane Molasses Derived N-Doped Graphene Quantum Dots: Dynamic Quenching Synergistically Photoinduced Electron Transfer for the Instant Detection of Nitrofuran Antibiotics.

The development of a highly selective, simple, and rapid detection method for nitrofuran antibiotics (NFs) is of great significance for food safety, environmental protection, and human health. To meet these needs, in this work, cyan-color highly fluorescent N-doped graphene quantum dots (N-GQDs) were synthesized using cane molasses as the carbon source and ethylenediamine as the nitrogen source. The synthesized N-GQDs have an average particle size of 6 nm, a high fluorescence intensity with 9 times that of undoped GQDs, and a high quantum yield (24.4%) which is more than 6 times that of GQDs (3.9%). A fluorescence sensor based on N-GQDs for the detection of NFs was established. The sensor shows advantages of fast detection, high selectivity, and sensitivity. The limit of detection for furazolidone (FRZ) was 0.29 µM, the limit of quantification (LOQ) was 0.97 µM, and the detection range was 5-130 µM. The fluorescence quenching mechanism of the sensor was explored by fluorescence spectroscopy, UV-vis absorption spectroscopy, Stern-Volmer quenching constant, Zeta potential, UV-vis diffuse reflectance spectroscopy, and cyclic voltammetry. A fluorescence quenching mechanism of dynamic quenching synergized with photoinduced electron transfer was revealed. The developed sensor was also successfully applied for detecting FRZ in various real samples, and the results were satisfactory.

Preparation of PVDF/Hyperbranched-Nano-Palygorskite Composite Membrane for Efficient Removal of Heavy Metal Ions.

In this work, three kinds of hyperbranched polyamidoamine-palygorskite (PAMAM-Pal) were designed and synthesized by grafting the first generation polyamidoamine (G1.0 PAMAM), G2.0 PAMAM and G3.0 PAMAM onto Pal surfaces, respectively. Then, these PAMAM-Pals were used as additives to prepare polyvinylidene fluoride (PVDF)/hyperbranched polyamidoamine-palygorskite bicomponent composite membranes. The structures of the composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TEM), X-ray photoelectron spectroscopy (XPS), field-emission scanning electronmicroscopy (SEM), atomic force microscope (AFM) and Thermogravimetric analysis (TGA). The adsorption properties of composite membranes to heavy metal ions was studied, and the results found that the maximum adsorption capacities for Cu(II), Ni(II) and Cd(II) could reach 155.19 mg/g, 124.28 mg/g and 125.55 mg/g, respectively, for the PVDF/G3.0 PAMAM-Pal membrane, while only 23.70 mg/g, 17.74 mg/g and 14.87 mg/g could be obtained for unmodified membranes in the same conditions. The high adsorption capacity can be ascribed to the large number of amine-terminated groups, amide groups and carbonyl groups of the composite membrane. The above results indicated that the prepared composite membrane has a high adsorption capacity for heavy metal ions removal in water treatment.